A hot water heater used in order to heat an interior of a motor vehicle circulates a heat exchanging medium (coolant) heated while passing through an engine to a heater core to heat introduced air. However, at the time of initial start-up of the motor vehicle, a significant time is required until the heat exchanging medium is heated.
As a method for complementing this, an electric heater or an electrical heater has been recently used. As an example, a positive temperature coefficient (PTC) heater electrically directly heating introduced air has been used as an auxiliary heating means together with or independently of the hot water heater. An example of Patent Documents which relates to the PTC heater includes Korean Patent Laid-Open Publication No. 2010-0055262, Korean Patent No. 1163448, and Korean Patent Laid-Open Publication No. 2006-0119163 filed by the present applicant, and the like.
Referring to FIG. 1, which is the related art, an air flow direction is denoted by an arrow, a rod assembly in which PTC devices 11 are assembled and a plurality of heat radiating fins 12 coupled to the rod assembly to radiate heat are coupled to each other by an adhesive means, and a housing 20 for enclosing and protecting the heat radiating fins 12 is further included. Generally, the heat radiating fins of FIG. 1 are called corrugated fins and have an advantage that a heat radiating area is increased due to a zigzag shape, but have disadvantages that manufacturing and assembling processes are complicated and a volume and a weight are large.
Further, in the related art, a heat source part including the PTC device is disposed in a direction that is in parallel with the air flow direction, such that an area of the heat source part has a direct effect on heat generation performance. Therefore, there was a limitation in decreasing a thickness (air flow direction) of a PTC heater.
Meanwhile, the PTC device according to the related art is generally received in a separate rod assembly for receiving the PTC device and is coupled to other heat radiating means by an adhesive, or the like. However, in the case in which the heat radiating means and the rod assembly are not closely adhered to each other due to a clearance or an air gap generated therebetween, heat exchange efficiency is decreased. In addition, a deviation may occur in heat radiating performance depending on an amount of applied adhesive means.
Further, at the time of repetition of thermal load, a phenomenon that adhesion is decreased occurs, such that durability is decreased, and performance deterioration and a defective product may be caused after an operation for a predetermined time.
In addition, in the case in which heat radiating performance is deteriorated, an electrical problem may occur, such that a plurality of heat radiating fins should be coupled by the adhesive means. Therefore, a work environment is not good, an assembling process is troublesome, and the number of components, a weight, and a cost are increased.